Enhancement of Postirradiation Longevity and Mating of the Boll Weevil (Coleoptera: Curculionidae) by Regulation of Preirradiation Feeding1

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Abstract
Feeding newly emerged male boll weevils, Anthonomus grandis grandis Boheman, a standard laboratory diet for 2 consecutive days before treatment with a 10-krad dose of gamma radiation was more detrimental to maintenance of postirradiation longevity than giving them just H2O or a 5% sucrose solution. The postirradiation LT50 for weevils given the standard diet was 9 days compared with 11 days for groups given H2O or sucrose before treatment and 12 days for those given 1% urea in a liquid diet. The mortality rate over a 14-day postirradiation period for the standard diet-fed group was significantly greater than weevils given only liquid diets. Mating propensity of male weevils given the various preirradiation diets did not differ from control mating at 5 days after irradiation. At 10 days after irradiation, reduced mating was exhibited by all treated groups and it ranged from 9% in standard diet-fed group to 42% in the urea/sucrose-fed group. Histological examination of the 14-day postirradiation, midgut pathology of weevils given the different diets revealed a greater survival of the regenerative cells and recovery of the midgut epithelium in groups given liquid diets containing urea. A range of 88–100% of the groups of weevils experiencing epithelial recovery also exhibited varying amounts of abnormal regeneration of the midgut nidi. Comparisons of the midguts of 3-day postemergent weevils given either the standard laboratory diet, H2O, or urea/H2O for 2 days showed significantly less mitotic activity and regeneration occurring in the epithelium of weevils given the two liquid diets before irradiation. The study suggests that weevils bearing an inactive midgut epithelium are more able to withstand the debilitating effects of the radiation treatment.